Gaseous electron tube structure



2 Sheets-Sheet 1 Filed Jan. 27, 1951 FIG. 2

. trvll.

INVENTOR. JAMES EMC LINDEN JR. 1

Sept. 22, 1953 J. E. MOLINDEN, JR 2,653,264

- GASEIOUS ELECTRON TUBE STRUCTURE Filed Jan. 27, 1951 2 Sheets-Sheet 2 FIG. 3 FIG. 4

- INVENTOR. JAMES E. MC LINDEN JR.

1977 aid/l5 Y Patented Sept. 22, 1953 GASEOUS ELECTRON TUBE STRUCTURE James E. McLinden, Jr., Rego Park, N. Y., assignor to Bendix Aviation Corporation, Teterboro, N. J., a corporation of Delaware Application January 27, 1951, Serial No. 208,159

10 Claims.

The invention relates to electron tubes, and more particularly to cold cathode discharge tubes.

One object of the present invention is to enclose the electrodes of a cold cathode discharge tube in a miniature envelope and provide connectors from the electrodes through the stem of the envelope to facilitate connecting the tube in an electric circuit.

Another. object is to adequately insulate and shield the inactive surfaces of the tube electrodes and connectors from one another to prevent long path discharges therebetween, while providing for cooperation of the active surfaces of the electrodes with one another.

A further object is to accurately space the electrodes from one another during assembly and maintain the electrodes in accurate spaced relation during the life of the tube by mounting the electrodes on rigid insulators of predetermined dimensions. 7

Another object is to facilitate construction of the tubes by unskilled personnel so that the spacing andconcentricity are consistent from tube to tube. 1 Still anotherobject is to assembly the electrodes and insulatorsflinto .a rigid mount structure and support the mount structure by the connectors.

1 Another object is to accommodateshifting of the connectors while sealing them in the. stem of the envelope, yet maintain the electrodes in fixed relation relative to one another.

Another object is to insulate the connectors from one another and from the tube electrodes independently of the mount structure to accommodate shifting of the connectors while they are being sealed into the envelope stem. The'invention contemplates an electron tube having a mount assembly including a plurality of electrodes and insulators for rigidly supporting the electrodes. The supports shield inactive surfaces of the electrodes and accurately space the electrodes from one another. The mount assembly is enclosed within an envelope and leads are provided extending through the stem ofthe envelope to connect the electrodes inan electric circuit. Insulating means is provided on the leads and the mount assembly is supported by the leads independently of the insulating means.

The foregoing and other objects and advantages of the invention will appear more fully hereinafter from a consideration of the detailed description which follows, takentogether with the accompanying drawings wherein .oneembodi- 2 ment of the invention is illustrated. It is tobe expressly understood, however, that the drawings are for the purposes of illustration and description only, and are not to be construed as defining the limits of the invention.

In the drawings, Figures 1 and 2 are longitudinal sections taken approximately on the lines I-l and 22 of Figure 3 through a cold cathode discharge tube constructed according to the invention and drawn to enlarged scale;

Figures 3 and 4 are transverse sections taken approximately on the lines 33 and 4-4, respectively, of Figure 1; and

Figure 5 is a schematic diagram showing the electrical connections between the electrodes and stem leads.

Referring now to the drawings for a more detailed description of the novel cold cathode discharge tube of the present invention, the tube is shown as comprising an envelope I, preferably of the miniature type, having a stem 3 at its base.

The envelope is evacuated and filled with helium at a pressure of approximately 15 mm. of mercury through a pinch seal 5 at its opposite end.

A plurality of stem leads 1, 9, ll, [3, 5, l1, l9 are sealed in stem 3 and each lead extends through a glass bead 2| integral with stem 3. Leads 9, I3, I! are cut off flush with the associated bead, and leads I, ll, IE, IS extend into the interior of the envelope. Mount leads 22, 23, 24, 25 are welded at 2-5 to stem leads 1, ll, I5, l9, respectively. A cylindrical ceramic insulator 21 having an axial opening '28 extending therethrough surrounds each mount lead and associated stem lead. Insulators 21 preferably are anchored to stem beads 2| by porcelain cement 29.

A cylindrical cathode support 31 of insulating material has a plurality of longitudinal apertures 33 receiving insulators 21 and mount leads 22, 23, 24, 25. The apertures are shouldered at 35 to engage eyelets 31 fixed to the mount leads to maintain cathode support 3| in fixed relation thereon. The cathode support is mounted direct- 1y on the mount leads, and the glass stem, which may soften while sealing the stem leads therein, need not be depended upon as a foundation for constructing and supporting the mount.

Cathode support 3| is recessed at 39 and receives a cathode pill 4| which may be substantially as described in applicants co-pending application Serial No. 785,051, filed November 10, 1947, and assigned to the same assignee as the present invention. The pill preferably includes by weight 76% cesium chloride, 4% aluminum -.on the cathode support.

powder and 20% nickel filings pressed into desired form. The pill is held in position by a nickel wire mesh screen 43 swedged in recess 39. Mount lead 24 connected to stem lead I is bent at right angles and extends through a cut-out portion 44 in cathode support 3| and transversely of the cathode support. The transversely extendingportion of the mount lead is welded or otherwise secured to screen 43 so that cathode pill 4| is connected electrically to stem lead I5. Porcelain cement 46 may be used about the portion of lead 24 adjacent screen-43 to insulate the lead and prevent long path discharge.

A cylindrical grid support 451o'f largerdiameter than cathode support 3| hasa plurality of spaced apertures 32 extending lengthwise there'through for receiving mount leads 22, 23, 25. The grid support is mounted on cathode support 3| and has an annular flange 41 encircling cathode-support 3| to position the grid support accurately The grid support .has an axial aperture 49 aligned with the active portionof cathode pill 4!.

of the grid within the grid support toward cathode pill 4|.

A connector 60 is welded or otherwisesecured to sleeve 56 and mount lead'25, whereby the grid is connected electrically to stem lead IS. The

connector also restrains movement of the grid .away from cathode pill 4|.

A keep-alive electrode 82 extends transversely of grid support 45 through an opening 5| into aperture 48 between cathode pill 4| and grid '53. A connector 63 from keep-alive electrode 62 extends lengthwise of grid support 45 through an aperture 134, and is connected to mount lead 23, whereby the keep-alive electrode is connected electrically to stem lead I An insulating anode support '65 is mounted in central aperture 55 in grid 53 and its movement toward cathode pill is limited by a shoulder on grid53. A tungsten anode II is fixed within a central aperture 13 within anode support 86.

A mica insulator B1 is mounted .on grid sup port 45 and is confined within'a flange -68 on grid support 45. Suitable openings 69 are provided in insulator 61 to receive mount leads 22, 23, 25, connectors 60, G3 and anode 'H. Mount :lead '22 is bent at right angles adjacent mica insulator 61 and is secured to anode H, whereby anode 1| is connected electricaliy'to stem lead 1.

A cylindrical top insulator I1 is mounted .on mica insulator 6! and is confined by flange 68 on grid support -45. Insulator 7,1 is recessed at 18 to receive anode ll and mount lead 22, and insulator "i1 is recessed at 18a, 18b to receive connectors 60, 63, respectively. A mica support 19 is mounted on topinsulator 1-1 and hasaplurality of radially extending tongues 8| yieldingly engaging envelope I. A getter assembly 83 is secured centrally to mica .support 19 by an-eyelet 84. Mount leads 23, .25 extend through suitable apertures in mica support 19 and top insulator 11 and a short rod 85 is welded to .eachmount lead 23, adjacent mica support 19. Porcelain cement 85 may be placed over the protruding ends of leads 23, 25 and associated rods 85 for insulating purposes.

The mount assem'blyis secured on mount leads 23,125 between eyelets'3'l and rods85. Mica support 19 is maintained under a slight tension by rods and eyelet 84 on getter assembly 83, the latter engaging insulator l1 and spacing the center portion of the mica away from the insulator. Vents 89 extending substantially radially through grid support 45 provide for circulating the gas fill into central aperture 49 between the electrodes.

The tubepreferably is assembled by assembling the supports and electrodes on the mount leads 22, 23, 24, 25 to complete the mount assembly. Insulators 21 are placed over mount leads 22, 23, 24, '25 in engagement with eyelets 31 and with the .ends :of the mount leads protruding therefrom. The protruding ends of the mount leads arewelded at 26 to *the associated stem leads and insulators .21 .are slid over the welds into engagement with beads 2| and are secured thereto by porcelain cement 29. The envelope then is assembled to the stem and the envelope is evacuated and filled with helium ata pressure of approximately :15 mm. =of mercury, as described above.

The inactive surfaces of the tube electrodes and connectors are adequately insulated and shielded from one another to prevent long path discharges therebetween while providing 'for cooperation of theactive surfaces of the electrodes. The stem leads are insulated by'insu'latorsfl and mount "leads 22, 23, -24, 25 are insulated bycathode support 3| and grid support '45. The inactive :portions of the cathode 'pill'are shielded by cathode support 3|. The portion of lead '22 connected to anode H is shielded "generally by top insulator l1 and from grid '53 by .=mica insulator .51, Anode 1| :is insulated by :anode support 66 and grid 53 is shielded .by grid support 45 and mica insulator '61. Suitable insulation is included :as :an integral part :of the mount structure, and the extensive use of extraneous "materials, such as non-emissive oxides and :porcelain cement which are fragile and :di'iiicult to apply, is avoided.

The rigid supports for the electrodes accurately locate the grid, cathode, anode and keepalive electrodes :during :assembly and maintain the electrodes accurately spaced and concentric during the life of the tube. The supports are interlocked with one another and provide a rigid mount :asseniblyso thatalthoughthe mount assembly may shift during assembly or :use, the relative spacings between the elements arefixed.

The arrangement described provides for readily assembling the tube by unskilled personnel and relieves the operator of the responsibility of establishing critical spacings of the electrodes'and other elements in thetube.

Although but one embodiment of the invention has been illustrated and described in :detail, it is to -be-expressly understood that the invention is not limited thereto. Various :changes can be made in thedesignand arrangement of the parts without departing from the spirit and scope of the invention as the same will now be understood by those skilled in the art.

What is claimed is.

'1. man electron tube, amount structure including a plurality .01 electrodes, an envelope enclosing said mount structure :and'having a stem, a plurality of leads extending through-said stem and connected to said electrodes and mounting said mount structure, insulating means on said leads .shielding said leads from one another throughout their =lengths,:and saidleads supporting said mount structure independently of said insulating meansra'nd saidenvelopeistem.

2. In an electron tube, a stem, leads extending through said stem, a mount assembly having leads extending from apertures therein and secured to said stem leads, insulators receivable in said apertures and slidable on said mount leads over the juncture of said mount leads and said stem leads, said insulators being of a length so that when the insulators are received a substantial distance within said apertures, said mount leads protrude therefrom, and when said insulators cover the juncture of said leads, said insulators extend part way into said apertures.

3. In an electron tube, a mount assembly including a plurality of electrodes and a rigid insulating support for each of said electrodes, said supports being arranged to rigidly support said electrodes and accurately space said electrodes from one another and shield all inactive portions of said electrodes, an envelope enclosing said mount assembly, and a plurality of leads extending through said envelope and connected to said electrodes, insulating means on said leads, and said mount assembly being supported by said leads independently of said insulating means.

4. In an electron tube, an envelope, a mount assembly in said envelope having a plurality of electrodes including an anode, a cathode and a grid and a rigid insulating support for each 01 said electrodes, said supports being arranged to support said electrodes independently of said envelope and accurately space the electrodes from one another and shield all inactive portions of the electrodes.

5. In an electron tube, an envelope, a rigid mount assembly in said envelope including an anode, a cathode in pill form, and a grid having an axial aperture, an insulating support mounting said cathode and shielding the inactive portions of said cathode, a grid support mounted on said cathode support and having an aperture aligned with the active portion of the cathode and receiving said grid, an anode support received in said grid aperture and supported by said grid and mounting said anode, said supports being of predetermined dimensions to accurately space said anode, cathode and grid in operating relation to one another.

6. Structure as described in claim 5 which ineludes a plurality of leads extending exteriorly of the envelope and connected to said anode, cathode and grid, and means for securing said mount assembly firmly to said leads.

'7. Structure as described in claim 5 which includes a plurality of leads extending exteriorly of the envelope and connected to said anode,

' cathode and grid, means for securing said cathode support to said leads, and insulators on said leads independent of said mount assembly.

8. In an electron tube, an envelope, a rigid mount assembly in said envelope including an anode, a cathode in pill form and a grid having an axial aperture, an insulating support mounting said cathode and shielding the inactive portions of said cathode, a grid support mounted on said cathode support and having an aperture aligned with the active portion of the cathode and receiving said grid, an anode support received in said grid aperture and supported by said grid and mounting said anode, said supports being of predetermined dimensions to ac curately space said anode, cathode and grid in operating relation to one another, insulating means on said grid support, a plurality of leads connected to said anode, cathode and grid and at least one of said leads extending through said mount assembly and having means for maintaining said mount assembly together.

9. In an electron tube, an envelope, a rigid mount assembly in said envelope including an anode, a keep-alive electrode, a cathode in pill form and a grid having an axial aperture, an insulating support mounting said cathode and shielding the inactive portions of said cathode, a grid support mounted on said cathode support and having an aperture aligned with the active portion of the cathode and receiving said grid, an anode support received in said grid aperture and supported by said grid and mounting said anode, said keep-alive electrode extending into said aperture between saidanode and cathode pill, said supports being of predetermined dimensions to accuratly space said cathode, anode and grid in operating relation to one another, insulating means on said grid support, a plurality of leads connected to said anode, keep-alive electrode, cathode and grid, and a pair of said leads extending through said cathode support, said anode support and said insulator and having means for maintaining said mount assembly together.

10. In an electron tube, a gas-filled envelope, a rigid mount assembly in said envelope including an anode, a cathode in pill form and a grid having an axial aperture, an insulating support mounting said cathode and shielding the inactive portions of said cathode, a grid support mounted on said cathode support and having an aperture aligned with the active portion of the cathode and receiving said grid, an anode support received in said grid aperture and supported by said grid and mounting said anode, said supports being of predetermined dimensions to accurately space said anode, cathode and grid in operating relation to one another, and at least one of said supports having a vent providing for circulation of gas fill into the aperture in said grid support and between said electrodes.

JAMES E. McLINDEN, J R.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,116,672 Ewest et al. May 10, 1938 2,409,466 Bahls Oct. 15, 1946 2,459,277 Halstead et al Jan. 18, 1949 2,560,346 Holdaway July 10, 1951 

